Heretofore, analog signals were used in multilocation conference arrangements to transmit both video and audio information. Consequently, when the video to be viewed is switched from one conference location to another the entire video picture was present and switched. In more recent conference arrangements, digital signals are employed to transmit the video information which do not usually contain complete picture information. Indeed, the digital signal usually includes only changes in the scene being viewed. Therefore, upon switching the digital signal, there is some disruption in the picture being viewed until the complete picture information is obtained.
None of these prior known arrangements resolve contention among multiple talkers at different conference locations or multiple requests for graphics transmission from different conference locations.
In one known arrangement, the video signal to be transmitted to conference locations is selected to be from a location having the first talker. While in another known arrangement the video is selected from the location having the loudest talker.
Problems arise in these prior arrangements when a number of conferees at different locations are concurrently talking. Indeed, the first talker or the loudest talker may not be the "right" or desired talker. This may lead to unnecessary switches in the video being transmitted before the "right" talker is selected. Such unnecessary switching adds undesirable disruption in the video being viewed. This is especially true in those conference arrangements which use digital signals to transmit the video information.
It is also important that after an interval of concurrent talkers the single retaining talker should be viewing a conference location he or she is responding or otherwise talking to and not some other location. This desired result may not be obtained in the prior known arrangements which have no mechanism for resolving contention among the locations for the video to be viewed.
Similar problems arise in conference arrangements including the transmission of graphics information. In one known conference arrangement, it is possible that during an interval of concurrent graphics transmission from different locations some of the conference locations may be viewing graphics information transmitted from one location while other conference locations may be viewing graphics transmitted from another location. This, of course, can be extremely undesirable. Additionally, multiple switches of the video being transmitted may be required before arriving at the "right" graphics transmission location. Again, in conference arrangements using digital transmission of the video information such unnecessary switching is undesirable because of the resulting disruptions in the video being viewed.